Quanitifying acoustic Doppler current profiler discharge uncertainty: A Monte Carlo based tool for moving-boat measurements

Colin Rennie, Stephanie Moore, Francois Rainville, David Mueller, Elizabeth Jamieson

Thursday 2 july 2015

9:15 - 9:30h at Africa (level 0)

Themes: (T) Special session, (ST) Acoustic monitoring of flow, turbulence and river discharge

Parallel session: 10F. Special session: Acoustic monitoring of flow, turbulence and river discharge

Assessing and quantifying the uncertainty associated with acoustic Doppler current profiler (ADCP) discharge measurements remains a significant challenge, given the large number of parameters that affect these measurements (e.g. instrument configuration, dynamic environment, operator decisions) and the difficulty in understanding their contribution to overall error or uncertainty. A Matlab based software tool (QUant), which uses Monte Carlo simulations, was developed to assess the relative contribution of 16 different parameters to the total uncertainty associated with moving-boat ADCP discharge measurements. Multiple data sets (where site conditions and operators were the same and varied) were analysed in order to evaluate the relative contributions of a range of error sources to the total uncertainty. Results indicated that uncertainty is dominated by the unmeasured areas of the flow, and in particular invalid data. This indicates that site selection remains important for high quality discharge measurements. This tool provides useful quantitative feedback on what parameters contribute most to uncertainty, and could be used by operators to determine the quality of their measurement and highlight what parameters could be modified (or improved) to reduce uncertainty.